Is the initiation or continuation of medical actions that have no other aim but to prolong the patient’s life when the patient is facing irreversible death.
To insist on prolonging merely biological human life at all costs is a serious assault on a person’s dignity.
Not everything which is technically possible is ethically admissible, and unjustified disproportionality, beyond what is medically reasonable, only prolongs the agony.
The appropriate individual and social approach to death avoids the performance of futile therapeutic measures, and supports limitation of therapeutic effort and proportionality based on palliative care.

Iglesias Lepine M., Echarte Pazos J. Medical and nursing care for patients expected to die in the Emergency Department. Emergencias 2007;19:201-210.